Vascular disease is one of the leading causes of death in the United States. The most common form of vascular disease is arteriosclerosis in which the blood vessels become partially or totally occluded. Left untreated, such blockages are a major contributing factor to angina, hypertension, heart attacks and strokes.
To treat this disease, many invasive surgical techniques have been developed. For example, cardiac bypass surgery is a commonly performed procedure whereby a blocked cardiac artery is bypassed with a healthy vessel obtained from another location in the patient's body. Because the chest cavity must be opened to perform cardiac bypass surgery, the procedure is not often performed on elderly or relatively frail patients.
To avoid the trauma associated with cardiac bypass surgery, several non-invasive techniques for removing blockages from a vessel have also been developed. One of the most promising is described in U.S. Pat. No. 4,990,134 issued to Auth. With this technique, an incision is made into the patient's femoral artery and a guide wire is advanced through the patient's vasculature to the site of the occlusion. Next, an atherectomy device including a catheter, a drive shaft and an abrasive ablation burr are threaded over the guide wire just proximal to the occlusion. The burr is then rotated by the drive shaft at high speed, typically 100,000-200,000 rpm and advanced over the occlusion. At this high rate of speed, the burr preferentially cuts the harder plaque material in the vessel while leaving the softer vessel tissue uncut.
It has been known for some time that fewer complications occur with the atherectomy procedure when the size of the catheter and the burr are minimized. A small catheter causes less damage at the point where it enters the body. In addition, a smaller catheter and burr can be navigated through smaller blood vessels with less chance of perforation.
While a smaller burr is generally preferable in atherectomy devices for decreasing the likelihood of complications, it limits the size of the lumen that is created in the vessel. Given these constraints, there is a need for an atherectomy device that can minimize the size of the catheter that needs to be introduced into the patient while simultaneously maximizing the size of the lumen that can be ablated in a vessel.